Removal of wax from oil



v No Drawing.

Patented May 10, 1932 UNITED STATES STAN-ARI) R. FUN STEN, F HAVERFORD,AND IVAN M. PERKINS, OF PENFIELD, PENN SYLVANIA, ASSIGNORS TO THEATLANTIC REFINING COMPANY, OF PHILADEL- PHIA, PENNSYLVANIA, ACORPORATION OF PENNSYLVANIA nnnrovnr. on wax mom OIL Our inventionrelates to the art of removing wax from wax-containing oil, aspetroleum, and more particularly to a process in which a substance isadded to the wax-containing oil, thereby to condition the oil so thatthe wax may be more readily removed therefrom.

We have found that by adding a compound contained in coal tar or acomponent thereof to a wax-containing oil before the oil is subjected toany of the well-known separating operations, then after such additionsubjecting the oil to a suitable separat ing operation, as for example,cold settllng, centrifuging, filtering, or the equivalent, the

7 wax will more readily separate from the oil than if such compound hadnot been added.

Furthermore, we have found that the coal tar compound may be added tothe waxcontaining oil in any suitable manner, as for example, by firstextracting coal tar with a suitable solvent such as benzol, alcohol,naphtha, or the like, and adding the extract to the wax-containing oil,or by filtering the wax-containing oil through coal tar or clay uponwhich the coal tar compound has been deposited, or by the directaddition to the oil of the coal tar compound or that portion of coaltar, as for example, coal tar pitch, which contains the compound. Ineither instance the coal tar compound is advantageously added towax-containing oil while the oil is hot, preferably while the oil is ata temperature above 70 F., and in any event above the temperature towhich the oil is to be chilled. We have found that it is preferable, tohave coal tar present in the wax-containing oil in amounts less than 2%by weight of the oil.

The chemical formula of component fractions of coal tar which functionmost advantageously in agglomeratin the wax is not known with precision.It is sufficient to say that the coal tar compounds or fractions thereofwhich are employed in accordance with our process are among the highermogeneral, that chilling of the wax-containing lecular weight,higher-boiling coal tar compounds' While the presence of the morevolatile, lower-boiling compounds of coal tar is not set forth'as ofparticular advantage in the separation of'wax, yet the presence of one1929. Serial No. 373,471.

or more such compounds in the coal tar compounds employed is notnecessarily undesirable. Herein, and in the appended claims it is to beunderstood that the coal tar extracts or compounds referred to whichcause agglomeration ofwax particles which in turn causes more readyseparation of wax from oil, refer in particular to the components of thecoal tar of boiling points or molecular weights, higher than those ofthe so-called tar pitch are at least in part or to substantial extentsuch compounds or extracts of higher boiling point and/or high molecularweight as will produce the desired agglomeration and/or separation ofwax from oil.

After the addition of the coal tar compound to the oil it may be treatedby any of the well-knownprocesses for removing wax from oil, as forexample, by the cold settling process which involves chilling the oiland allowing it to stand, or by the centrifuging process which involveschilling the oil then passing it into a centrifuge, or by filtering theoil-wax mixture after chilling through a suitable filtering medium.

In separating wax from oil by processes involving chilling thetemperature to which the wax-containing oil is chilled depends largelyupon the particular pour desired of the ultimate oil product. We havefound, in

oil to F. or below according to the pour desired, will producesatisfactory results by our process. However, we are not limited to anyspecific temperatures of chilling.

A particular advantage of our process is that the Wax content of thewax-containing oil forms larger crystals or crystal aggregates duringchilling so that separation of solid 5 from liquid may be more readilyefi'ected, as for example, by such'well-known separating processes ashereinbefore stated.

. As an example of our process but without intending to limit ourinvention thereto, a m lubricating oil containing Wax, more particularlya high viscosity fraction obtained from the non-cracking distillation ofa mid-continent crude petroleum was diluted with naphtha using 70 partsof naphtha to 30 parts of oil. The dilutedoil was raised in temperatureto about 130 F. and while at this temperature the oil was filteredthrough a bed of equal parts of coal tar pitch and clay such as fullersearth, of about ten inches in depth.

It is estimated that the oil after filtering contained about .3% of thedesired coal tar compound. The oil was then cooled to +10 F. andmaintained at that temperature in a settling pan for a period of twentyhours. Af-

ter such period it was found that the wax had settled to the bottom ofthe oil forming a distinct lower layer, while the upper layer was aclear substantially wax-free liquid and comprised about 54% of the totaloil. A blank run under the same conditions except that no coal tarcompound was added thereto showed no appreciable settling during thesame period of time.

As specific examples of'the sources of the coal tar compound used in ourprocess, such may be obtained from coal tar residues, or pitches,preferably of high melting point, as of the order of 400 F., or fromhigh boiling point coal tar distillates, as for instance of a boilingpoint of the order of from 620 40 to 650 F. when distilled under avacuum of 10 m, m. of mercury. Either the residue or the distillate maybe incorporated with the wax-containing oil thereby to dissolve in thelatter the desired coal tar material in suitable amounts, as for exampleby methods hereinbefore stated. I

Thus it will be seen that 'byadding a compmnfl derived from coal tar toa wax-containing oil there results the particularly desirableefiectofconditioning the oil so that the wax may be more readilyseparated therefrom both with regard to rate and completeness ofseparation.

It will be understood that in some instances itmay be. found unnecessaryto dilute the wax-containing oil before chilling and therefore we do notcontemplate limiting our invention in this respect. Furthermore, it isto be understood that our process may be used for the separation of-waxfrom wax-containing oil or mixture of wax-containing oils, moreparticularly for the removal of wax from petroleum oil, either crudepetroleum or any wax bearing portion thereof, or mixture of them.

What we claim is:

1. A process for dewaxing a wax-containing oil involving separation ofwax from oil, which comprises adding to the oil a highboiling compoundcontained in coal tar, thereby to condition the wax-containing oil tocause wax agglomeration, thereafter removing wax from the oil.

2. A process for dewaxing a wax-containing oil involving separation ofwax from oil, which comprises adding to the oil a highboiling compoundcontained in coal tar, thereby to condition the wax-containing oil tocause wax agglomeration, chilling the oil, thereafter removin wax fromtheoil.

3. A process for ewaxing a wax-containing oil involving separation ofwax from oil, which comprises adding coal tar to the oil, thereby tocondition the wax-containing oil to cause wax agglomeration, chillingthe oil, thereafter removing wax from the oil.

4. A process for dewaxing a wax-containing oil involving separation ofwax from oil which comprises, adding to the oil to the extent of lessthan 2% by weight thereof, a compound contained in coal tar pitch,thereby to condition the wax-containing oil to cause wax agglomeration,chilling the oil, and thereafter removing wax from the oil.

5. A process for dewaxing a wax-containing oil involving separation ofwax from oil,

which comprises adding to the oil a comp] pound contained in coal tarpitch, thereby to condition the wax-containing oil to cause waxagglomeration, chilling the oil, thereafter filtering the wax from theoil.

6. A process for dewaxing a wax-containing oil involving separation ofwax from oil, which comprises dissolving in the oil a highboilingwax-agglomerating compound contained in coal tar, thereby to conditionthe wax-containing oil to cause wax agglomeration, thereafter removingwax from the oil.

7. A process for dewaxing a wax-containing oil involving separation ofwax from oil, which comprises dissolving in the oil a high-boilingwax-agglomerating compound contained in coal tar, thereby to conditionthe wax-containing oil to cause wax agglomeration, chilling the oil,thereafter removing wax from the oil.

8. A process for dewaxing a wax-contain- I ing oil involving separationof wax from oil which comprises adding to the oil a high-boils ingwax-agglomerating compound contained in coal tar. thereby to conditionthe wax-containing oil to cause wax agglomeration, keeping said oil attemperature in excess of 10 F. during addition of said compound,thereafter chilling the'oil to a temperature below 10 F., and removingwax from the oil.

9. A process for dewaxing a wax-containingoil involving separation ofwax from oil, which comprises dissolving in the oil an extract of coaltar containing a. high-boiling wax-agglomerating compound of coal tar,thereby to condition the wax-containing oil to cause wax agglomeration,keeping said oil at a temperature in excess of 10 F.-during the additionof said extract, thereafter chilling the oil to a temperature below 10F., and removing Wax therefrom.

10. In the art of dewaxing wax-containing oils involving separation ofwax from oil, the step of preparing the oil for separation of waxtherefrom, which comprises adding coal tar pitch to the oil, thereby tocondition the waxecontain ing oil to cause wax agglomeration.

11. In the art of dewaxing a wax-containing. oil involving separation ofwax from oil the step of preparing the oil for separation o waxtherefrom, which comprises adding to the oil a wax-agglomerating extractof coal tar containing at least one of the higher boiling compounds ofcoal tar, thereby to condition the wax-containing oil to cause waxagglomeration.

12. In a process for dewaxing a wax-containing oil involving separationof wax from oil, the steps which comprise diluting the oil with asolvent which will not to substantial extent react with the oil,adding-to the

